The headline on PFT was posted in the wee hours Monday morning. It reads "League quietly shifts focus of helmet-to-helmet hits." Here's Florio:

Per a league source, the NFL no longer tells officials to err on the side of protecting players when assessing whether a defenseless receiver has been struck in the head or neck area, or on any part of his body with the defender’s helmet.

[...]

If the officials had thrown the flag without prohibited conduct occurring, they would have nevertheless received a downgrade. Erring on the side of safety no longer applies — possibly because the goal is to avoid erring of any kind. Instead, the league’s new focus will be aggressively enforcing the rule.

You'll recall that the league instituted a new rule this offseason that prohibits players from leading with the crowns of their helmets when delivering hits. This is in addition to rules already on the books about hitting defenseless receivers. These rules are in place because even though football is an inherently violent game, the NFL is determined to place the onus of player safety on the players themselves. And it's up to the officials to enforce these rules in the name of player safety. Those officials must make a split-second decision to determine whether a hit is or isn't against the rules. But now the league is telling those same officials not to err on the side of player safety because making a mistake can negatively affect those officials' grades. And all of this is to make sure all these rules are properly enforced.